JP5074682B2 - Silicone release composition and silicone release plastic film using the same - Google Patents

Abstract

Disclosed are a silicone release composition and a silicone release plastic film using the same. The silicone release composition comprises a vinyl group-containing polysiloxane, hydrogen polysiloxane, epoxycyclohexyl group-containing silane, platinum catalyst, and polyether or lauryl ether. When the silicone release composition is coated on an oriented polyester film during a manufacturing process thereof in an in-line coating mode, a release film having excellent silicone curing characteristics, interfacial adhesion between a silicone layer and plastic film and peel characteristics can be obtained.

Description

  The present invention relates to a new silicone release composition and a silicone release plastic film using the same. More specifically, the present invention relates to stability over time and rub-off physical properties after aging. The present invention relates to an excellent silicone release polyester film.

  In general, the silicone release agent is divided into a silicone main chain, a silicone curing agent, a catalyst and the like. In the case of the main chain, vinyl polysiloxane or hexenyl polysiloxane containing a vinyl group is used, and the curing agent is hydrogen polysiloxane.

  A general release layer is obtained by applying a release agent to a substrate such as a plastic film, a sheet, paper, or a nonwoven fabric. As a known example, a technique has been announced in which a silicone layer is applied to a base material, that is, a plastic film, cellulose, and paper (Patent Documents 1, 2, 3, and 4). In addition, a silane coupling agent was used to improve the adhesion between the silicone layer and the substrate (Patent Documents 5 and 6). However, as a general silane coupling agent, there is a problem that it falls off from the silicone layer and the polyester base material because of the poor chemical resistance of alcohols with strong polarity and poor stability of the coating liquid. In addition, it was difficult to produce the coating liquid for a long period after it was produced once. In short, when a substance disclosed in Patent Documents (described below) that secures the above-mentioned silicone release characteristics is used, the stability of the coating liquid is poor and it is difficult to apply the coating for a long time.

U.S. Pat.No. 3,076,726 U.S. Pat.No. 3,169,884 U.S. Pat.No. 3,427,270 U.S. Pat.No. 3,900,617 U.S. Pat.No. 4,677,160 U.S. Pat.No. 5,672,428

  The present invention has been made in view of such conventional techniques, and the object thereof is to apply a silane coupling agent having a unique structure, and to improve the adhesion between the silicone and the polyester base material, and the chemical resistance characteristics. And providing a release composition with improved coating solution stability.

  Another object of the present invention is to provide a plastic film to which the release composition is applied.

  The above-mentioned object of the present invention is achieved by a release composition containing polysiloxane, a silane containing one or more epoxycyclohexyl groups, a surfactant, and a catalyst.

  Another object of the present invention is achieved by applying the composition to a plastic film, such as a polyester film, by in-line coating.

  The beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane or beta- (3,4-epoxycyclohexyl) -alkyltriacetoxysilane used by the present inventor is used for release coating. Smoothness can be secured, and a uniform adhesive force between the interface between the polyester substrate and the silicone layer can be secured. In addition, from the opposite side of the silicone coating layer, it is difficult to secure static electricity and runnability, which can be said to be the biggest disadvantages of the polyester base material. Costs and problems can be reduced.

  Further, in the case of commercial silicone, there is no possibility of 100% curing, so not only residual hydrogen polysiloxane but also residual vinyl polysiloxane or hexenyl polysiloxane should remain after curing. When unreacted substances are exposed to the atmosphere for a long period of time, they are electrically charged with “-” charges, and dust and foreign substances in the atmosphere are almost charged with “+” charges. A strong bond is caused to play a role of crosslinking between the release film or release paper and the pressure-sensitive adhesive. At this time, a very high release force is expressed, but when using the above-mentioned release assembly liquid, since the curing characteristics are excellent even when exposed to bad air, the stability of the peeling force is also improved. Even better.

  In addition, the rotational energy between silicon atoms and oxygen atoms, which can be said to be a feature of the molecular structure of silicone (polysiloxane), is almost 0 kJ, which results in poor gas permeability after substrate coating and drying, and polyester After the reaction with such a structure and hydrogenpolysiloxane as a curing agent, the delayed rub-off phenomenon due to the hydrolysis reaction due to the influence of moisture (the dried silicone release film is left under the influence of moisture for a considerable period of time. In the case of coating and drying, the silicone coating is used by using a silane coupling agent with a unique molecular structure. The adhesive strength at the interface between the layer and the polyester could have excellent properties.

  Furthermore, the release film according to the present invention can be upgraded and differentiated in various release film markets, such as adhesive labels, polarizing films (MLC), MLCCs (Multi-Layer-Ceramic Capacitors). In various fields such as carrier release used during manufacturing, solar control adhesive film, and LCD protective release film, degree of over-lamination, medical passiness, FPC protective film, and ECG protective film Available.

The inventor has found that the silicone release composition contains a silane containing one or more epoxycyclohexyl groups, such as beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane, or beta When-(3,4-epoxycyclohexyl) -alkyltriacetoxysilane is added and the release agent is coated on a substrate such as a polyester film, the interfacial adhesive force between the polyester film and the release agent is It was confirmed that it was possible to produce a release film that was greatly increased and extremely excellent in peel strength.

  The surfactant is preferably polyether or lauryl ether, and the catalyst is preferably platinum, rhodium or tin.

  Most preferred examples of the silicone release agent according to the present invention include hexenyl polysiloxane or vinyl polysiloxane release agent, 4 to 30% by weight, hydrogen polysiloxane, 0.3 to 3% by weight, platinum catalyst 0.002% to 0.005%, and beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane, or beta- (3,4-epoxycyclohexyl) -alkyltriacetoxysilane, 0.003% to 0.00. 5% by weight is included.

  The weight ratio of the silane containing an epoxycyclohexyl group to the polysiloxane is preferably 0.1 to 10 parts by weight of a silane containing an epoxycyclohexyl group to 100 parts by weight of the polysiloxane.

  The vinyl polysiloxane release agent has an average particle size of 0.01 to 1 μm, and the silicone composition liquid of the present invention is a laminate of polyester, polypropylene, polyethylene, polyvinyl chloride, nylon, polycarbonate, and plastic Films; Kraft papers; Non-woven fabrics, cloths, and other materials can be applied directly to the substrate. The total solid content is 4 to 30% by weight, more preferably 6 to 20% by weight.

  If it is less than 4% by weight, there is a problem in uniform coating (Coverage).

  Beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane, or beta- (3,4-epoxycyclohexyl) -alkyltriacetoxysilane, is an interface between a silicone polymer and a substrate such as PET. When 0.001 to 1% by weight, preferably 0.003 to 0.5% by weight, is used as the chemical substance capable of improving the contact force, safety in physical properties can be secured. Moreover, when it is 0.003% or less, the base material adhesion force between PET and silicone is inferior, and thus unreacted silicone is extracted. Furthermore, when 0.7 weight% or more was used, when it used during the manufacturing process of PET film, it has confirmed that a crack arises in a silicone film during an extending process and after an extending process. From this, it was found that the peeled physical properties were significantly inferior. The release agent is applied to the substrate after corona treatment or plasma treatment is performed to form a strong chemical bond between the substrate and the release layer. The thickness of the substrate can be 2 mm or less, preferably 12 to 1500 μm. Further, a chemical treatment layer of a primer layer such as the above-mentioned beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane for strengthening a normal chemical bond on the surface of the release layer formation of the base material Can also be preceded.

  The mold release composition is preferably applied at a thickness of 0.1 to 2 μm after the stretching and drying steps, and the surface number average roughness of the polyester film coated with silicone is preferably 0.1 to 2 μm. More preferably, the thickness is 0.01 to 1.0 μm. After drying, when the coating film thickness is 2 μm or more, the silicone coating surface and the surface on which the silicone coating is not applied are wound at a constant pressure, resulting in a blocking phenomenon. In addition, it can be confirmed that a rub-off phenomenon occurs after aging (24 hours, 50 ° C., 95% RH). The rub-off phenomenon of the silicone layer occurs due to insufficient adhesion between the silicone layer and the substrate, and does not use beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane. It turns out that it became a problem especially (refer an Example and a comparative example). Moreover, as a process condition which coats a mold release liquid and extends | stretches simultaneously with thermosetting drying, extending | stretching is 2.5-12 times, drying and hardening temperature conditions are 60 to 250 degreeC, a wind speed is 8 to 40 m / s, The residence time in the dryer is 0.5 seconds to 10 minutes, more preferably about 1 second to 1 minute.

  Of the thermal stability evaluation items of the polyester release film produced after in-line application using the silicone composition, the thermal shrinkage in the longitudinal direction is 0.5 in the thermal shrinkage measurement. The heat shrinkage rate in the transverse direction is preferably -0.03% to 1.0%, and more preferably, the heat shrinkage rate in the longitudinal direction is 0.3% to 1%. The heat shrinkage ratio of the steel sheet is -0.01% to 0.4%.

  It was found that when the thermal shrinkage rate was 0.5% or more at 150 ° C. in the transverse direction for 30 minutes, it was not preferable for the degree of release using a hot melt pressure-sensitive adhesive. This is because the hot melt adhesive in the lateral direction is bonded to the release film in the vertical direction, and at the same time, the silicone layer and the polyester layer of the release film have different thermal conductivities when instantaneously shrinking or expanding. It is due to being.

式中、ｎは０以上の整数(integer)であり、Ｐは１以上の整数である。 The structure of beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane used in the present invention is as follows.

In the formula, n is an integer of 0 or more, and P is an integer of 1 or more.

A typical structure is as follows.

式中、Ｒ１はＣＨ＝ＣＨ_２であり、Ｒ２はＣＨ_２‐ＣＨ_２‐ＣＨ_２‐ＣＨ_２‐ＣＨ＝ＣＨ_２、ＣＨ_３である。ここで、ｐとｑとは、０以上の整数である。 The following typical silicone structures were used.

In the formula, R 1 is CH═CH ₂ , and R 2 is CH ₂ —CH ₂ —CH ₂ —CH ₂ —CH═CH ₂ , CH ₃ . Here, p and q are integers of 0 or more.

  The silicone release composition of the present invention containing the material having the above structural formula was applied by in-line coating during the production process of the polyester film. The in-line coating has no problem even when it is applied during the gravure, wire bar, grooved, comma, MPG (Multi Pressure Gravure) 5R / 0 or 6R / 0 coating process.

  The plastic film to be coated with the composition is a uniaxially stretched film obtained by subjecting an unstretched sheet to corona treatment or plasma treatment, or a biaxially stretched film subjected to corona treatment or plasma treatment, and immediately before the simultaneous biaxially stretched film. Corona or plasma treated films are all possible.

  The base materials used in the experiments are XD500-23 μm, 30 μm, 38 μm, and 50 μm base materials that are commercially available for MCC release carriers manufactured by Toray Sehan Co., Ltd., developed by the present inventors.

Evaluation test For the peel force measurement, model AR1000 (manufactured by Chem. Instrument) was used, and a standard adhesive tape, TESA7475 (trade name) was bonded to the surface of the silicone release film under a load of 2 kgf. The peel force before and after thermal aging was measured using a vessel (model; HC4033, manufactured by Heraeus). The measurement is performed by sampling at a width of 4 cm × 15 cm, under a peeling angle of 180 °, a peeling speed of 0.3 m / min, and a measurement dimension is 100 mm (length) × 25.4 mm ( Width), and the peel force unit was g / inch. The measured value was evaluated five times before calculating the average value.

After release force silicone coating of the adhesive tape, the adhesive tape TESA7475 to the silicone coated surface of the cured film adhered with a load of 2 kgf. Next, after placing a 70 g / cm ² iron bar on the release film and leaving it at 23 ° C. and 50% RH for 24 hours, using a model AR1000 (manufactured by Chem. Instrument), a peeling angle of 180 ° The peeling force was measured at a peeling speed of 0.3 m / min.

Grasping the silicone curing characteristics After sticking the adhesive tape (model; manufactured by 810, 3M) on the silicone release layer and peeling it off, drop a drop of the test reagent on the adhesive tape with a microsyringe as shown below. The degree of cure is determined by the spot size. That is, it can be said that the spot size is determined by the degree to which the unreacted silicone on the adhesive of the tape is desorbed. Generally, when the test reagent is dropped onto the tape, the spot size is reduced. Is large, but when there is unreacted silicone, the spot size should be small.
Test reagent = IPA + Violet dye constant ratio IPA => The silicone coating surface cannot be dissolved. However, the 810 tape adhesive made by 3M is dissolved. Depending on the relative size of the spots, expressed as excellence, Ryoko, normal, less (see Table 1 below).

Rub-off after aging
When model-TH-I-180 (manufactured by JEIOTECH) is used and the silicone-coated film is left at 50 ° C and 95% RH for 2 months and then rubbed strongly with fingertips, the silicone layer from the polyester film layer It is possible to confirm the adhesive property between the cured silicone and the PET film through a rub-off test.

Chemical resistance chemical resistance, MEK, impregnated toluene, IPA, 1,4 BD (the 1,4-butanediol) on the swab, by rubbing strongly silicone coating layer was determined from dropping whether silicone.

  According to Examples 1 to 3, the silicone release liquid containing beta- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane is coated on the corona-treated polyester surface, thereby increasing the interfacial adhesion. In addition to being excellent, it was confirmed that the release properties were extremely excellent.

  That is, when the silicone release layer improves the interfacial adhesive force by chemical bonding to the polyester film, peeling can be easily performed after bonding with the standard adhesive tape at the time of peeling force measurement. In addition, the stability of the silicone layer can be ensured even when it is rubbed strongly with a fingertip after being left for two months at 50 ° C. and 95% RH.

  According to Comparative Examples 1 to 3, when a silicone composition that does not contain beta- (3,4-epoxycyclohexyl) ethyltrimethoxysilane was used, an unstable coating pattern (Ribbing) phenomenon occurred, and the peeling force Instability was confirmed in the change with time.

  In Comparative Examples 1 to 3, beta- (3,4-epoxycyclohexyl) ethyltrimethoxysilane was not used, and the physical properties changed according to the viscosity of the wet silicone composition and the coating thickness after drying. As a result of observing the stability over time, the rub-off phenomenon remarkably appeared as the coating film thickness increased.

It is drawing which showed the hardening characteristic experiment method of silicone.

Claims (6)

And 30 percent by weight polysiloxane 4, a hydrogen polysiloxane 0.0 2 by weight%, to silane 0.003 containing an epoxycyclohexyl group and 0.5% by weight, a surfactant, to catalyst 0.002 0 0.005% by weight of a silicone release composition comprising:
The polysiloxane is hexenyl polysiloxane or vinyl polysiloxane,
The silane containing an epoxycyclohexyl group may be a beta- (3,4-epoxycyclohexyl) -alkyltrialkoxysilane having the following formula, or a beta- (3,4-epoxycyclohexyl) -alkyltriacetoxysilane, or a mixture thereof. Yes,
The catalyst is characterized by a platinum, a silicone release composition.

(In the above formula, n is an integer of 0 or more, P is an integer of 1 or more, and the trialkoxy group may be a methoxy group, an ethoxy group, an acetoxy group, or a combination thereof.)   2. The silicone release composition according to claim 1, wherein the surfactant is polyether or lauryl ether.   The composition according to claim 1 is coated with a constant thickness on one or both surfaces of the surface layer part through an in-line coating process during the plastic film manufacturing process to form a silicone release layer. Release film.   The plastic film coated with the composition is a uniaxially stretched film obtained by corona treatment or plasma treatment on an unstretched sheet, a biaxially stretched film subjected to corona treatment or plasma treatment, and a corona or plasma immediately before simultaneous biaxial stretching. The plastic release film according to claim 3, which is a film that has been treated.   The plastic release film according to claim 3, wherein the plastic film is a polyester, polyethylene, polypropylene, nylon, polycarbonate, polyvinyl chloride, or polyvinyl alcohol (PVA) film.   The plastic release film according to claim 3, wherein the dried coating film thickness is 0.06 to 2 µm.

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